When a photon is created, it instantly achieves the speed of light -- How?

Click For Summary

Discussion Overview

The discussion revolves around the nature of photons and their speed upon creation, specifically addressing the question of whether photons instantly achieve the speed of light without a process of acceleration. The scope includes conceptual clarifications and technical explanations related to the properties of light and photons.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants assert that photons, being light, inherently travel at the speed of light and do not undergo a process of speeding up.
  • One participant compares the creation of a photon to ripples in water, suggesting that the speed is immediate rather than gradual.
  • Another participant challenges the idea that a photon's speed is dependent on its energy, emphasizing that all light, regardless of energy, travels at the speed of light.
  • There is a claim that emitted light is a wave and that photons are created only upon interaction, which contrasts with the notion of photons as discrete particles moving at light speed.
  • A participant acknowledges a lack of rigor in their previous statements and clarifies that they did not intend to imply that speed depends on energy.
  • There is a question raised about what process could be considered as already moving at the speed of light, indicating confusion or disagreement about the nature of photon creation.

Areas of Agreement / Disagreement

Participants express differing views on the nature of photons and their speed upon creation, with no consensus reached on whether photons are best understood as particles or waves, or how their speed relates to energy and the process of emission.

Contextual Notes

Some statements reflect assumptions about the nature of light and photons that may not be universally accepted, and there are unresolved questions regarding the conceptualization of emitted light versus photons.

zuz
Messages
100
Reaction score
36
I've been told that when a photon of light is created it instantly achieves the speed of light without having to 'speed up". How is this possible?
 
Science news on Phys.org
Pedantically, photons are just light, so whatever speed they go is the speed of light.

To answer the question you are asking, however, the photons are emitted with a certain amount of energy. The process which goes into the photon being created requires the energy that makes it go as fast as it does.
 
zuz said:
I've been told that when a photon of light is created it instantly achieves the speed of light without having to 'speed up". How is this possible?

When you drop a pebble onto the surface of water, do you notice the ripple being created speeding up, or do you see it immediately moving at the a particular speed?

There is also no "why" or "how" in this case, the same way we do not have the why's and how's for light having a fix, constant speed in vacuum.

James Chase Geary said:
Pedantically, photons are just light, so whatever speed they go is the speed of light.

To answer the question you are asking, however, the photons are emitted with a certain amount of energy. The process which goes into the photon being created requires the energy that makes it go as fast as it does.

This is false, or misleading at best. It somehow implies that its speed depends on its energy, which is wrong. There is nothing to indicate light having a lower energy limit to make it go at c. All light, no matter how low its energy, moves at c.

Zz.
 
  • Like
Likes   Reactions: davenn and russ_watters
zuz said:
I've been told that when a photon of light is created it instantly achieves the speed of light without having to 'speed up". How is this possible?
Just to add to what others have said, emitted light is not a photon, it's a wave. That is, there are no photons in a beam of light. The wave only creates a photon when it interacts with something. This is important because a lot of people, I think possibly including you, think that the emitted "photon" is like a little tiny billiard ball that goes shooting off at the speed of light.
 
  • Like
Likes   Reactions: davenn
My apologies for my lack of rigor. I wasn't trying to be misleading, just trying to get at the concept in an intuitive way. But yes, of course, the speed doesn't depend on the energy. I just meant to imply that photons were created by a some kind of process already moving at light speed.
 
James Chase Geary said:
I just meant to imply that photons were created by a some kind of process already moving at light speed.

which also is not good
what do/did you think was already moving at c ?
 
  • Like
Likes   Reactions: phinds

Similar threads

Graduate Measuring the speed of light in a straight line
  • · Replies 19 ·
Replies
19
Views
2K
Undergrad Achieving the speed of light at the end of a whip
  • · Replies 15 ·
Replies
15
Views
6K
Graduate How does the speed of light change when it enters glass?
  • · Replies 12 ·
Replies
12
Views
3K
Graduate Why does the speed of light change in different media?
  • · Replies 4 ·
Replies
4
Views
4K
Graduate Mass, Light Speed, and the Mystery of Photons Explained
  • · Replies 19 ·
Replies
19
Views
2K
High School I still don't understand the propagation of light
  • · Replies 13 ·
Replies
13
Views
2K
High School Is light breaking its own speed limit when cornering?
  • · Replies 25 ·
Replies
25
Views
2K
Undergrad Measurement of the Speed of light
  • · Replies 4 ·
Replies
4
Views
1K
Undergrad What is the lifetime of a photon in a medium?
  • · Replies 3 ·
Replies
3
Views
2K
High School How is a Photon being created?
  • · Replies 3 ·
Replies
3
Views
5K